Present rapidly oscillated optical scanning mirrors relying on mechanical linkages and mechanisms suffer from joint compliance and excessive inertial reaction forces due to masses associated with the scanning mirror. Although the solution, which immediately comes to mind, is to eliminate all masses which are not absolutely necessary to the operation of the scanning mirror, the manner of eliminating these masses is the subject matter of the present inventive concept. In order to achieve a constant angular velocity over a major portion of an oscillatory stroke of a mirror, the mirror must be angularly decelerated, stopped and accelerated in the opposite direction in the smallest practical portion of a scan cycle and be essentially free of external forces in the largest practical portion of a scan cycle. In the concept presented herein, this is effected by an impulse momentum reversal of short stroke springs. The energy losses that occur during the constant velocity portion of the scanning cycle are replaced by piezoelectric actuators or thrust generating means.
An optical scanner with constant velocity linear scanning may find many different uses. The most popular use being in television. While present projectors for very large screen television are presently implemented using electronic scanning, the present invention of mechanically oscillating reflective means could be substituted. Galvanometers are commonly used for beam deflection although here the scan is typically sinusoidal. The ability of the scanner of the present invention to scan through very large angles at a constant velocity greatly increases its usability over prior art devices. In addition, the present inventive concept allows use in a micro G environment where the piezoelectric actuators control the mirror motion in all six degrees of freedom. In such a situation, the energy losses of bearings could be eliminated and the scanning device can provide further improvements over present scanning devices.
It is therefore an object of the present invention to provide an improved optical scanning reflector.